Problem: Kevin is 5 times as old as Ben and is also 36 years older than Ben. How old is Ben?
Explanation: We can use the given information to write down two equations that describe the ages of Kevin and Ben. Let Kevin's current age be $k$ and Ben's current age be $b$ $k = 5b$ $k = b + 36$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $b$ , and both of our equations have $k$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $5b$ $-$ $ (b + 36)$ which combines the information about $b$ from both of our original equations. Solving for $b$ , we get: $4 b = 36$ $b = 9$.